Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Nat Mater. 2010 May;9(5):397-402. doi: 10.1038/nmat2721. Epub 2010 Feb 28.
Understanding new superconductors requires high-quality epitaxial thin films to explore intrinsic electromagnetic properties and evaluate device applications. So far, superconducting properties of ferropnictide thin films seem compromised by imperfect epitaxial growth and poor connectivity of the superconducting phase. Here we report new template engineering using single-crystal intermediate layers of (001) SrTiO(3) and BaTiO(3) grown on various perovskite substrates that enables genuine epitaxial films of Co-doped BaFe(2)As(2) with a high transition temperature (T(c,rho=0) of 21.5 K, where rho=resistivity), a small transition width (DeltaT(c)=1.3 K), a superior critical current density J(c) of 4.5 MA cm(-2) (4.2 K) and strong c-axis flux pinning. Implementing SrTiO(3) or BaTiO(3) templates to match the alkaline-earth layer in the Ba-122 with the alkaline-earth/oxygen layer in the templates opens new avenues for epitaxial growth of ferropnictides on multifunctional single-crystal substrates. Beyond superconductors, it provides a framework for growing heteroepitaxial intermetallic compounds on various substrates by matching interfacial layers between templates and thin-film overlayers.
理解新型超导体需要高质量的外延薄膜，以探索其内在的电磁特性并评估器件应用。迄今为止，铁基超导薄膜的超导性能似乎因外延生长不完善和超导相的连通性差而受到影响。在这里，我们报告了一种新的模板工程，使用(001)SrTiO3 和 BaTiO3 单晶中间层在各种钙钛矿衬底上生长，从而实现了 Co 掺杂 BaFe2As2 的真正外延薄膜，具有较高的转变温度（T(c,rho=0)为 21.5 K，其中 rho 为电阻率）、较小的转变宽度（DeltaT(c)=1.3 K）、较高的临界电流密度 J(c)为 4.5 MA cm(-2)（4.2 K）和较强的 c 轴磁通钉扎。实施 SrTiO3 或 BaTiO3 模板以匹配 Ba-122 中的碱土层与模板中的碱土/氧层，可以为在多功能单晶衬底上外延生长铁基超导材料开辟新途径。除了超导体之外，它还为通过匹配模板和薄膜覆盖层之间的界面层，在各种衬底上生长异质外延金属间化合物提供了一个框架。
